This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). EB CME is clinical content presented with practice recommendations supported by evidence that has been systematically reviewed by an AAFP-approved source. The practice recommendations in this activity are available online at
http://www.ahrq.gov/clinic/uspstf05/pad/padrs.htm.

This statement summarizes the USPSTF recommendations on screening for peripheral arterial disease and the supporting scientific evidence and updates the 1996 recommendations contained in theGuide to Clinical Preventive Services, 2nd ed.1 Explanations of the ratings and of the strength of overall evidence are given in Tables 1 and 2, respectively. The complete information on which this statement is based, including evidence tables and references, is included in the brief evidence update2 on this topic, available on the USPSTF Web site at
http://www.uspreventiveservicestaskforce.org. The recommendation also is posted on the Web site of the National Guideline Clearinghouse at
http://www.guideline.gov.

This recommendation was first published by: Agency for Healthcare Research and Quality, Rockville, Md., August 2005.

Summary of Recommendation

The USPSTF found fair evidence that screening with ankle-brachial index can detect adults with asymptomatic PAD. The evidence also is fair that screening for PAD among asymptomatic adults in the general population would have few or no benefits because the prevalence of PAD in this group is low and because there is little evidence that treatment of PAD at this asymptomatic stage of disease, beyond treatment based on standard cardiovascular risk assessment, improves health outcomes.

The USPSTF found fair evidence that screening asymptomatic adults with the ankle-brachial index could lead to some small degree of harm, including false-positive results and unnecessary work-ups. Thus, the USPSTF concludes that, for asymptomatic adults, harms of routine screening for PAD exceed benefits.

TABLE 1

USPSTF Recommendations and Ratings

The USPSTF grades its recommendations according to one of five classifications (A, B, C, D, or I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms).

A.

The USPSTF strongly recommends that clinicians provide [the service] to eligible patients.The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms.

B.

The USPSTF recommends that clinicians provide [the service] to eligible patients.The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms.

C.

The USPSTF makes no recommendation for or against routine provision of [the service].The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes that the balance of benefits and harms is too close to justify a general recommendation.

D.

The USPSTF recommends against routinely providing [the service] to asymptomatic patients.The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh benefits.

I.

The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service].Evidence that [the service] is effective is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined.

TABLE 1
USPSTF Recommendations and Ratings

USPSTF Recommendations and Ratings

The USPSTF grades its recommendations according to one of five classifications (A, B, C, D, or I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms).

A.

The USPSTF strongly recommends that clinicians provide [the service] to eligible patients.The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms.

B.

The USPSTF recommends that clinicians provide [the service] to eligible patients.The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms.

C.

The USPSTF makes no recommendation for or against routine provision of [the service].The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes that the balance of benefits and harms is too close to justify a general recommendation.

D.

The USPSTF recommends against routinely providing [the service] to asymptomatic patients.The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh benefits.

I.

The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service].Evidence that [the service] is effective is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined.

USPSTF = U.S. Preventive Services Task Force.

TABLE 2

USPSTF Strength of Overall Evidence

The USPSTF grades the quality of the overall evidence for a service on a three-point scale (good, fair, or poor).

Evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies; generalizability to routine practice; or indirect nature of the evidence on health outcomes.

Poor:

Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes.

Evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies; generalizability to routine practice; or indirect nature of the evidence on health outcomes.

Poor:

Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes.

USPSTF = U.S. Preventive Services Task Force.

Clinical Considerations

• The ankle-brachial index, a ratio of Doppler-recorded systolic pressures in the lower and upper extremities, is a simple and accurate noninvasive test for the screening and diagnosis of PAD. The ankle-brachial index has demonstrated better accuracy than other methods of screening, including history taking, questionnaires, and palpation of peripheral pulses. An ankle-brachial index value of less than 0.90 (95 percent sensitive and specific for angiographic PAD) is strongly associated with limitations in lower-extremity functioning and physical activity tolerance.

• Smoking cessation and lipid-lowering agents improve claudication symptoms and lower-extremity functioning in patients with symptomatic PAD. Smoking cessation and physical activity training also increase maximal walking distance in men with early PAD. Counseling for smoking cessation, however, should be offered to all patients who smoke regardless of the presence of PAD. Similarly, physically inactive patients should be counseled to increase their physical activity regardless of the presence of PAD.

Discussion

PAD refers to atherosclerotic occlusive disease of the arterial system distal to the aortic bifurcation and is a relatively common disorder in older persons.3 The American Heart Association estimates that as many as 8 to 12 million Americans have PAD and that nearly 75 percent of them are asymptomatic.4 An estimated 1 million Americans develop symptomatic PAD every year. Specifically, the prevalence of lower-extremity PAD based on ankle-brachial blood pressure ratios is approximately 10 to 20 percent of community-dwelling persons 65 years and older and 18 to 29 percent of patients 50 years and older in general medical practices.5–7 The disease spectrum ranges from mild, intermittent claudication resulting in calf pain to severe, chronic leg ischemia requiring arterial bypass or amputation. Risk factors associated with PAD include older age, cigarette smoking, diabetes mellitus, hypercholesterolemia, hypertension, and (possibly) genetic factors.3 There are no significant gender differences in the overall prevalence of PAD in the general population. Over a five-year period, 25 to 35 percent of persons with PAD will have a myocardial infarction or stroke, and an additional 25 percent will die, usually from cardiovascular causes.8–10

Screening may be conducted by such instruments as history taking, questionnaires, or the ankle-brachial index. Results from one study found that the sensitivity and positive predictive value of a classic history of claudication were only 54 and 9 percent, respectively, when using the ankle-brachial index as the gold standard.11 The Edinburgh Claudication Questionnaire (ECQ), which is a modification of the World Health Organization/Rose Questionnaire, has been validated in a study of approximately 300 patients older than 55 years who saw their physician for any complaint. When compared with the independent assessment of two blinded health care professionals, the ECQ showed a sensitivity of 91 percent and a specificity of 99 percent for the diagnosis of intermittent claudication.12 Ankle-brachial index has demonstrated better accuracy than the combination of history taking and physical examination. The sensitivity of an abnormal posterior pulse was 71 percent, the positive predictive value was 48 percent, and the specificity was 91 percent. An abnormal dorsalis pedis had a sensitivity of only 50 percent; this artery is congenitally absent in 10 to 15 percent of the population.1 Both the sensitivity and specificity of an ankle-brachial index less than 0.9 (the accepted cutoff for the presence of PAD) is about 95 percent for detecting angiographic arterial disease.13 The accuracy of this screening tool increases as lower extremity stenotic lesions worsen.

One randomized clinical trial (RCT) of treatment of men with early PAD detected by screening investigated the impact of population-based screening.14 The control group received usual care, and the intervention group received advice to stop smoking and keep walking for exercise. The study found improved ambulation in the intervention group; however, the study did not address the impact of interventions on PAD or cardiovascular disease events. In another RCT of primary prevention of intermittent claudication, a subgroup analysis of 26,289 male smokers 50 to 69 years of age who had no history or symptoms of intermittent claudication, there was no benefit of using vitamin E, beta carotene, or both to prevent intermittent claudication.15

Recommendations from Other Groups

The American Diabetes Association currently recommends annual screening that includes a history of claudication and palpation of pedal pulses for PAD in persons with diabetes.16 The American Academy of Family Physicians recommends against the use of Doppler or duplex ultrasonography or other vascular laboratory tests for PAD in asymptomatic persons.17 A few organizations, such as the American Heart Association and the Society of Interventional Radiology, support the use of the ankle-brachial index in the evaluation of suspected PAD. For further information, please refer to the following Web sites: American Heart Association (http://www.americanheart.org), American College of Surgeons (http://www.facs.org/index.html), and Society of Interventional Radiology (http://www.sirweb.org).

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The U.S. Preventive Services Task Force recommendations are independent of the U.S. government. They do not represent the views of the Agency for Healthcare Research and Quality, the U.S. Department of Health and Human Services, or the U.S. Public Health Service.

The series coordinator is Charles Carter, M.D., University of South Carolina Family Medicine Residency, Columbia, S.C.

This is one in a series excerpted from the Recommendation Statements released by the U.S. Preventive Services Task Force (USPSTF). These statements address preventive health services for use in primary care clinical settings, including screening tests, counseling, and chemoprevention. This statement is part of AFP’s CME.
See “Clinical Quiz” on page 387.